1. Technical Field
The technical fields relates to an intermediate adapter used for using an interchangeable lens which is not directly fitted to a camera body, that is to be interposed between the camera body and the interchangeable lens.
2. Related Art
In order to use an interchangeable lens that is not directly fitted to a camera body, an intermediate adapter that is interposed between the camera body and the interchangeable lens has been known. The intermediate adapter is used in such a way that the intermediate adapter is first attached to the camera body and then the interchangeable lens is attached to the intermediate adapter. The intermediate adapter is provided with terminals corresponding to the respective signal terminals, power-supply terminals and the like of the camera body and the interchangeable lens. Communication between the camera body and the interchangeable lens are conducted through the terminals of the intermediate adapter.
JP-A-07-234432 discloses structure of an intermediate adapter including a CPU as one aspect of the intermediate adapter. In the camera system disclosed in JP-A-07-234432, although the intermediate adapter has the CPU, the communication between the camera body and the interchangeable lens is conducted not through the CPU. Therefore, since no communication delay is raised and the structure of the intermediate adapter becomes simpler. The CPU in the intermediate adapter communicates with a CPU in the camera body by using a three-wire serial method so that correction data are transmitted to the CPU of the camera body.
After the interchangeable lens is attached to the camera body through the intermediate adapter interposed therebetween, power-supply voltage is supplied from the camera body to the interchangeable lens through the intermediate adapter. However, when the power-supply voltage is supplied from the camera body to the interchangeable lens while attaching the interchangeable lens to the camera body, the power-supply voltage is erroneously supplied to terminals other than the power-supply terminals, causing a failure. Therefore, the camera body needs to supply the power-supply voltage to the interchangeable lens after recognizing the attachment of the interchangeable lens to the adapter. Consequently, it is important to detect accurately attachment of the interchangeable lens to the adapter.